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This research focuses on biochemical changes related to quality loss in frozen (−18 °C for 9 months) sardine (Sardina pilchardus) previously subjected to high-pressure (HP) processing (125–200 MPa). The inhibition (p < 0.05) of lipid hydrolysis development (lower free fatty acid formation and lipase activity), observed in frozen sardine as a result of the previous HP treatment, increased with the pressure level applied. Several parameters including peroxide value, thiobarbituric acid index, fluorescent compounds, and polyenes showed that the applied HP conditions prior to sardine freezing did not increase lipid oxidation. Also, HP did not induce a substantial modification of acid phosphatase and cathepsins B and D activities, and the electrophoretic patterns of sarcoplasmic and myofibrillar protein fractions did not change. However, HP processing led to a decrease in myofibrillar protein content in frozen pressure-treated fish, an effect that was higher in 175- and 200-MPa treated samples. In conclusion, this research showed that pressure treatments in the 125–200-MPa range with holding time of 0 min cause only minor modifications in biochemical indicators of deterioration throughout the subsequent frozen storage of samples for up to 9 months. This study shows the need to optimize HP conditions, particularly in the case of applications combining HP treatments, frozen storage, and thawing to obtain products with high quality and commercial viability

This research focuses on biochemical changes related to quality losses observed in Atlantic mackerel (Scomber scombrus) muscle stored under commercial frozen storage conditions (9 months, −18 °C) when subjected to high-hydrostatic pressure (HHP) treatments (125, 150, 175, and 200 MPa for 0 min) before freezing. After freezing, free fatty acid (FFA) formation (lipid hydrolysis assessment) showed a marked inhibition in HHP-treated fish and during frozen storage of samples treated at 175 MPa. Fluorescence ratio (FR) assessment of tertiary lipid oxidation showed a partial inhibitory effect during the 0–9-month period for samples treated at 175 and 200 MPa. After a 3-month storage of samples treated at these pressure levels, one-dimensional SDS-PAGE analysis of the sarcoplasmic protein fraction revealed the disappearance of a band; additionally, samples treated at 150 MPa showed the same effect at month 9. After gel excision, trypsin digestion, tandem mass spectrometry (MS/MS), and sequence database analysis, the band was identified as phosphoglycerate mutase 2 (28.7 kDa). On the other hand, HHP processing did not show a significant effect on trimethylamine (TMA) values, primary and secondary lipid oxidation, PUFA levels, 1-D myofibril protein pattern, and the activity of acid phosphatase and cathepsins B and D. Biochemical quality indices such as FFA, TMA, and FR and the activity of acid phosphatase and cathepsin B showed a progressive increase throughout the frozen storage of all samples

We determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish species

The assessment of enzymatic activity on Atlantic horse mackerel (Trachurus trachurus) during frozen storage was carried out in samples pre-treated by high-pressure processing (HPP) combinations of 150, 300 and 450 MPa with 0-, 2.5- and 5-min holding time (untreated samples were used as controls). The activities of four enzymes (acid phosphatase, cathepsins B and D, and lipase) in fish muscle were quantified during accelerated storage conditions (up to 3 months at −10 °C). The experimental data were fitted to second-order polynomial models to determine the effect of pressure level, holding time and frozen storage time on these enzyme activities and to identify conditions of maximum/minimal enzyme inactivation. Acid phosphatase and cathepsin (B and D) activities were significantly (p < 0.05) influenced by HPP, showing behaviours during frozen storage different from control samples. Acid phosphatase and cathepsin B activities decreased (p < 0.05) with HPP treatments, being this effect more intense for cathepsin B, particularly at 450 MPa. Regarding cathepsin D, the activity increased (p < 0.05) at intermediate pressure (300 MPa) and decreased (p < 0.05) at higher pressure (450 MPa). During frozen storage, cathepsin D enzymatic activity tended to increase over time indicating activity recovery of these enzymes. Although a predictive model for its activity was not acceptable, the increase in lipase activity during storage was the most pronounced trend observed.

We determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish species

In this work, we studied the effect of high-pressure processing (HPP) pre-treatments (150, 300 and 450 MPa for 0, 2.5 and 5 min) on key enzyme activities in Atlantic mackerel (Scomber scombrus) during frozen storage (3 months of accelerated storage, − 10 °C). Except for a minor decrease from treatment at 450 MPa, no substantial effect on acid phosphatase activity was observed. In contrast, cathepsins B and D and lipase were affected by HPP and frozen storage. Increasing the pressure reduced cathepsin B and lipase activities. Generally, increasing the holding time at 150 MPa increased the activity of cathepsin B and lipase (except at month 1), while increasing the holding time at 300 MPa reduced the lipase activity, and no effect was observed at 450 MPa. Overall, cathepsin D activity increased with frozen storage time and for treatments at 300 MPa but decreased at 450 MPa. This work provides novel information of HPP pre-treatments application, lowering enzyme activity during frozen storage of Atlantic mackerel

Frozen storage of horse mackerel (Trachurus trachurus) is limited by lipid damage causing sensory quality losses. This work deals with changes in functional and sensory properties during frozen storage of horse mackerel treated by high hydrostatic pressure processing (HPP) prior to freezing. Three levels of pressure (150, 300, and 450 MPa), pressure holding time (0.0, 2.5, and 5.0 min), and frozen storage time (0, 1, and 3 months) were studied. Expressible water, colour parameters, mechanical texture parameters and sensory parameters were evaluated in raw and cooked samples. The texture profile analysis of raw and cooked HPP samples suggested that a product texture similar or close to fresh muscle is possible. The sensory analysis showed that a 150 MPa treatment yielded high acceptability values. Although acceptability decreased during frozen storage, values remained close to those of fresh samples. Industrial relevance Frozen storage of fatty fish species is known to be strongly limited by the lipid damage development, being this an important drawback for its commercialisation as such or for its further employment as raw material in other kinds of processing (canneries, smoking, etc.). Present research provides novel and valuable information concerning the employment of high hydrostatic pressure technology applied before freezing and frozen storage to improve some functional and sensory properties in horse mackerel muscle indicating that it can be a useful alternative for fish processors seeking to better utilise this resource.

This work focuses on the effect of a previous high pressure processing (HPP) on the lipid damage development occurring during the frozen storage (−10°C; up to 3 months) of Atlantic horse mackerel (Trachurus trachurus). HPP conditions included different pressure (150, 300, 450 MPa) and pressure holding time (0.0, 2.5, 5.0 min) values. During frozen storage, horse mackerel muscle was analyzed for lipid hydrolysis (free fatty acid assessment; FFA) and oxidation (formation of peroxides, thiobarbituric acid reactive substances, and fluorescent compounds), and polyene content. An inhibition of lipid hydrolysis development was observed; thus, both an increasing pressure level and pressure holding time led to a marked inhibition of FFA content throughout the frozen storage. Concerning the lipid oxidation development, a partial inhibition was also obtained during the frozen storage (months 1 and 3) by increasing the pressure level applied (namely, fluorescent and peroxide compound formation); however, pressure holding time did not lead to a definite trend. No effect of HPP treatment was concluded on the polyene content of the fish muscle lipids. Present research provides novel information concerning the employment of HPP technology focused on the inhibition of lipid damage during a subsequent frozen storage

The frozen storage of Atlantic mackerel (Scomber scombrus) is limited by lipid damage causing sensory quality losses, an important drawback to its commercialisation. This work deals with changes in functional and sensory properties during freezing and frozen storage of Atlantic mackerel pre-treated by high hydrostatic pressure processing (HPP). Three levels of pressure (150, 300, and 450 MPa), holding time (0.0, 2.5, and 5.0 min), and frozen storage time (0, 1, and 3 months) were tested. Expressible water, CIE colour parameters, mechanical texture parameters and sensory parameters were evaluated. Results showed that HPP at 150 MPa lowered the expressible water of raw samples by 40% and thus improving the quality of frozen muscle. During frozen storage, the flesh colour of the controls (no HPP) tended to yellowness, while 150 MPa treatments yielded samples with lightness similar to fresh muscle. HPP effects on the colour parameters were negligible. Hardness and chewiness values of HPP-treated samples and no-HPP controls were similar. Sensory analysis suggested that 150 MPa did not affect the flesh odour. Most importantly, the sensorial acceptability of oven cooked HPP-treated samples was better than that of frozen fillet controls and similar to that of fresh mackerel.

This work focused on assessing lipid damage during the storage of frozen Atlantic mackerel (Scomber scombrus) subjected to a high hydrostatic pressure (HHP) treatment (150, 300, 450 MPa with holding times of 0.0, 2.5, and 5.0 min) prior to freezing. The extent of lipid hydrolysis (free fatty acids) and oxidation (peroxide, thiobarbituric acid reactive substance and fluorescent and browning compound formation) as well as the polyene content were analysed during 3 months of accelerated storage at − 10 °C. A marked inhibition (p < 0.05) of free fatty acids and tertiary lipid oxidation compound formation during storage was observed when increasing the pressure level or the pressure holding time of the HHP treatment. However, only minor differences in the polyene index and no effect (p > 0.05) in the content of primary and secondary oxidation compounds were observed.

Soluble proteins from surimi wash water (SWW) can be insolubilized by complexing with chitosan-alginate allowing its recovery and the reduction of the organic matter in the processing water discharged from surimi processing plants. The objective of this work was to evaluate the effect of adding soluble proteins recovered from Pacific whiting SWW on the mechanical and functional properties of commercial Alaska Pollock surimi grade FA. Levels evaluated were 0 (control), 10, 30 and 50 g insolubilized SWW solids/kg Alaska Pollock grade FA surimi. The mechanical and functional properties of Alaska Pollock surimi pastes and gels were characterized by texture profile analysis (TPA), puncture test, expressible water (EW) and color attributes. TPA and puncture test parameters increased significantly (P≤0.05) when 10–30 g/kg of soluble proteins from Pacific whiting SWW were added. EW values increased also, indicating a decrease of the water holding capacity. Color parameters showed that all surimi gels increased in redness, an undesirable effect in the production of Alaska Pollock grade FA surimi, Las proteínas solubles del agua de lavado del surimi (ALS) pueden ser insolubilizadas por medio de la formación de complejos con quitosano y alginato. Su recuperación por este método permite reducir la materia orgánica en el agua de proceso. El objetivo de este trabajo fue evaluar el efecto de la adición de proteína soluble recuperada del ALS de Pacific whiting sobre las propiedades mecánicas y funcionales de surimi comercial de Alaska Pollock de grado FA. Los niveles de adición evaluados fueron 0 (control), 10, 30 y 50 g sólidos insolubilizados de ALS/kg de surimi de Alaska Pollock de grade FA. Las propiedades mecánicas y funcionales se caracterizaron por medio del análisis de perfil de textura (TPA), prueba de punción, agua extraíble y atributos de color. Los valores de los parámetros de TPA y prueba de punción incrementaron significativamente (P≤0.05) cuando se adicionaron de 10 a 30 g/kg de proteínas solubles de ALS de Pacific whiting. El agua extraíble también se incrementó, indicando un descenso de la capacidad de retención de agua. Los atributos de color indicaron que todos los geles de surimi incrementaron su color rojo, lo cual podría ser desfavorable para la producción de surimi de Alaska Pollock grado FA